Replying to Stomach cramps

okay, im a runner and usually whenever i go on my runs these days i end up getting severe stomach cramps, like on my abs. it usually happenes after 15 mins or so and there is nothing in my stomach because i usually go in the mornings before breakfest, i drink water before and after but they get so bad that i have to go to the point of walking. it is espically shitty when i get them in a race or track and field. i dunno i was just wondering if you guys had any ideas cause this is shitty for my performance. thanks guys!